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Least-cost decarbonisation - Germany's future energy system: 100% renewable | feasible | safeguarding security of supply | optimised

How to design Germany's future energy system to achieve decarbonisation at the lowest possible cost to society? How can security of supply of an industrial nation like Germany be safeguarded, despite the highly fluctuating nature of renewable energy sources like wind, solar and hydro power?


  • E.ON Group Innovation GmbH
  • EWE Netz GmbH
  • Netz Leipzig GmbH
  • Robert Bosch GmbH
  • Schleswig-Holstein Netz AG


To answer these questions in an open and unbiased manner, six leading companies from the German energy and automotive industries have conducted an innovative, cross-sectoral study with WECOM and share the results to spark public discussion.



From a purely technical and political perspective, there are numerous design options for the future decarbonised German energy system. Previous studies on the German energy future are based on only partially optimised results or use various sector models that each only cover a sub-sector of the energy system.

The aim of WECOM and its project partners was therefore to determine, for the first time ever, a totally optimised decarbonised energy system in fine regional resolution for Germany. Taking into account regional differences, all sectors of the energy system (i.e. also end-use technologies and grids) were to be optimised and this optimisation of all sectors was to be carried out simultaneously in one closed model.



  • The determination of the least-cost, 100% renewable, feasible and resilient energy system was carried out entirely by mathematical optimisation without any pre-determined results. For more than 150 modelled technologies along the entire energy value chain the optimal capacity was computed for each region - without requiring any forecasts on their use or non-use.
  • This computation (with over 4 million decision variables) was achieved by WECOM's planning tool WALERIE, which was developed within five previous international projects, incorporating the expertise of more than 35 energy companies.
  • WALERIE is a fully integrated (sector coupled), entirely data-driven, regionalised planning tool that includes an integrated grid model and optimal asset dispatch.
  • WALERIE considers forecasting risks of input parameters already during the calculation and is ideally suited for efficient scenario calculation and stability analyses.
  • The parameterisation of WALERIE for Germany is based on state-of-the-art level of science and research from more than 250 external studies, as well as the expertise of our project partners.



The present analyses show an exclusively economically and technically optimised energy system. A broad mix of technologies and energy sources is used to supply regionally and segmentally diverse energy needs without fossil fuels and at least-cost to society. The economically optimised energy system is much more efficient than today's, far less dependent on imports and, due to the high degree of diversification, also resilient to changes in technical, economic and political framework conditions.


  • About three quarters of primary energy is generated domestically, which means that dependence on imports is massively reduced in comparison to today (-80% energy imports).
  • Domestic potentials for the generation of green power is heavily utilised; expansion paths for wind power and photovoltaics must be accelerated.
  • The flexibilisation of the electricity system and the provision of necessary storage capacity is largely enabled by renewable gases: 33% of primary power is used in electrolysis plants (approx. 3 500 full-load hours); gas-fired power plants are expanded and become hydrogen-ready but use much less gas over the course of the year than today.
  • In addition to domestic hydrogen, biomethane is also produced in Germany to a significant extent. The agricultural land use for energy crops remains at today's level.
  • Grid requirements for power and district heating are increasing. For gas grids, numerous decentralised feed-ins and the partial conversion to hydrogen-readiness pose new challenges.

Based on this least-cost energy system without technological pre-determinations further political framework conditions, alternative concepts or considerations of market acceptance can be integrated and transparently examined regarding their consequences – as a basis for a rational, fact-based discourse on Germany's future energy system.


  • 150

    technologies modelled

  • > 4 m.

    optimisation decisions taken

  • > 250

    external studies for parameterisation

  • 6

    project partners

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